This invention relates generally to control apparatus for regulating the air intake in oil burners of heating boilers and, more particularly, to such regulating apparatus which employ a closure member which is axially movable with respect to the air intake aperture of the oil burner in response to the actuation and deactuation of the heating boiler.
It is of course well known to utilize heating boilers equipped with oil burners for the central heating systems of buildings, such for example, as single family dwellings. In such applications it is conventional to regulate the interior temperature by actuating and deactuating the oil burner of the boiler through the use of a temperature responsive or thermostatic switch which monitors the temperature of the boiler water.
Conventional oil burners utilized in connection with heating boilers are of course provided with air intake apertures for the purpose of providing a flow of air through the boiler to accomplish combustion of the oil. However, upon the temperature of the water in the boiler reaching the desired level whereby the thermostatic switch deactuates the oil burner rendering it inoperative, a flow of air will normally still be maintained through the oil burner. Such air flow through the burner while the boiler is in its inoperative condition tends to cool the boiler thereby resulting in an overall decrease in the efficiency of the system. The fact that it is not unusual for the temperature in the boiler room of a single family dwelling to be relatively low further aggravates this deleterious decrease in boiler efficiency by cooling the boiler water more rapidly than if the surrounding environment were at a higher temperature. Cooling of the boiler water when the boiler is in its inoperative mode of course results in a more frequent actuation of the thermostatic switch thereby resulting in a substantially continuous operation of the oil burner which of course results in a higher consumption of fuel oil then would be otherwise necessary.
The flow of air through the oil burner can be prevented by closing either the flue gas passage of the air intake aperture of the oil burner. Since closing the flue gas passage requires relatively specialized equipment which is rather complex and therefore expensive, this solution has not been found practical, especially in the case of single family dwellings.
Accordingly, apparatus have been designed to provide a closure for the air intake aperture of the oil burner. Thus, for example, in one previously proposed design, a flap has been eccentrically pivoted to the air intake duct which tends to remain closed under the force of gravity but which will open by virtue of the suction forces supplied by the blower upon actuation of the boiler. However, this design has proven rather unreliable in service due to the fact that it has been necessary to construct the flap of heavy material so that it tends to remain positvely closed under all conditions, such as in windy weather. The use of such a heavy flap in connection with the air intake aperture of the oil burner has proven to have an unfavorable effect on the operation of the latter. A typical draft valve utilized on the intake side of the blower of the oil burner is illustrated in Swedish Pat. Nos. 173,033 and 176,218.
Other attempts have been made to provide closure apparatus for the air intake aperture of oil burners for regulating the air intake thereto. For example, German Pat. No. 918,955 discloses a closure plate for opening and closing the intake aperture in response to the actuation and deactuation, respectively, of the heating boiler. In this particular design, the movement of the closure plate is accomplished utilizing pneumatic means. Additionally, hydraulically controlled closure plates are currently being utilized in connection with the regulation of intake air to the oil burner.
However, regardless of whether the control of the movement of the closure plate is effected by the suction provided by the blower or through the use of hydraulic or pneumatic cylinders, such prior apparatus have been found not to be satisfactory. Thus, as mentioned above, the use of suction to control the movement of the closure plate has been found to be unreliable, requiring the use of a safety switch. The use of hydraulic and pneumatic systems for controlling the movement of the closure plate requires relatively expensive ancillary equipment which is often awkward if not impossible to provide on existing burners. Of course, in connection with hydraulic and pneumatic systems, external energy sources are required or, alternatively, such systems must be connected to the oil pump of the burner itself which is relatively cumbersome and expensive.
It has therefore been proposed to utilize centrifugal force in connection with the operation of the closure plate of the intake aperture of an oil burner. Thus, in designs employing the centrifugal force principle, there is no need for the provision of external energy to accomplish the movement of the closure plate. Such a design is disclosed in U.S. Pat. No. 3,149,662, which describes apparatus wherein the opening and closing of the intake aperture of the oil burner is accomplished through the use of centrifugal force. However, the design disclosed therein is structurally complex and, therefore impractical.